Critical Thickness Of Paraffin Deposition Research For The Waxy Crude Oil Pipeline

The heated waxy crude oil pipelines transport high pour point and high viscosity oil,in which the paraffin deposits is easy to come into being. The thickness of paraffin deposition have an important effect on the pipeline's normal operation and shutdown and restart process. So this paper will do research on critical thickness of paraffin deposition for heated waxy crude oil pipelines,and hope to guide pipelines to run safely.The rheology study of the crude oil in Qing—Jing pipeline involves two aspects: one is rheology characteristics with dynamical shear and temperature dropping, the other is the yielding characteristics of the gelled crude oil when restarting the pipeline. Firstly, measure the rheology of Xiangfan crude oil and analyze the influence of different preheating temperature on the rheology. Secondly, it is analyzed that the influence of preheating temperature, pre-shear rates and restart shear rates on the restart characteristics of the Xiangfan crude oil.We build the maths model of the temperature field of the soil outside the buried hot oil pipeline and the maths models of the flow field and the temperature field of the oil in the pipeline, and get the coupling solution respectively using FDM and FVM. It is analyzed that the influence of different wax thickness on the temperature drop after shutdown and the restart process of the pipeline in winter and summer. We get the duration time and the critical wax thickness of the hot oil pipeline.